Current electronic devices continue to become more prevalent in day-to-day activities. For example, smart phones and tablet computers continue to grow in popularity, and provide everyday personal and business functions to its users. These electronic devices typically include large screens or displays utilized by the user to interact (e.g., input/output) with the electronic devices.
Conventionally these screens or displays are made from reinforced or modified glass. However, these glass screens may still be susceptible to damage. Specifically, these conventional screens may scratch, chip or crack when an undesirable impact event or force (e.g., drop, crushed) occurs with the electronic device. Damage to the screens of the electronic device may render the device partially, or completely, inoperable and/or may prevent the user from utilizing the electronic device for its intended purposes.
The use of the crystalline form of alumina (Al2O3) (e.g., Corundum), commonly known as sapphire, is becoming more of a viable option for replacing the glass screen or display. Specifically, with improved manufacturing processes of single crystal sapphire, and the improved elemental characteristics (e.g., hardness, strength) of sapphire over glass, sapphire may be an acceptable replacement material for conventional glass screens and displays. However, the same chemical/elemental characteristics that make sapphire a superior material choice over glass, also make the manufacturing of sapphire difficult. For example, sapphire utilized to make screens for electronic device typically undergo a final annealing process before further cosmetic process are performed. During this annealing process, the top surface of the sapphire may “heal,” or fill in micro-cracks formed during other processes (e.g., lapping, cutting, planing). More specifically, surface atoms of the sapphire may be substantially mobile during the annealing process and may rearrange themselves to fill in the micro-cracks formed on the top surface.
However, in addition to filling these micro-cracks, the surface atoms may rearrange themselves during the annealing process to form a plurality of terraced protrusions in the top surface. These terraced protrusions may vary dependent upon a plurality of factors including, but not limited to, the crystallographic orientation of the sapphire and the operational characteristics (e.g., time, temperature, atmosphere) of the annealing process. While some terraced protrusions formed on the top surface of the sapphire may not negatively affect the quality of the sapphire, other protrusions may cause cosmetic defects in the sapphire. For example, some terraced protrusions may create colorful light reflections on the surface the sapphire. These reflections may negatively impact the sapphire when used as a screen or display for an electronic device by obstructing a user's ability to see the content featured on the screen of the electronic device clearly. That is, when a colorful light reflection occurs on the sapphire structure, that reflection may block or prevent a user from seeing at least a portion of the content being displayed on the screen. As a result, the functionality of the electronic device is diminished because of the cosmetic defect caused by the terraced protrusions formed on the sapphire's top surface.